JP2020124567A - Strontium sealed source - Google Patents

Abstract

To concentrate the radiation on a diseased tissue, without using isotropic radiation which most likely expose surrounding healthy tissues to unnecessary radiation.SOLUTION: The disclosure pertains to a strontium-90 sealed radiological or radioactive source 100 which may be used in treatment of an eye or other medical or industrial processes. The sealed radiological source includes an annular strontium radiological insert 130 and an encapsulation 102 thereof. The encapsulation has increased shielding in the center thereof.SELECTED DRAWING: Figure 3

Description

This application claims priority under U.S. Patent Law Section 119(e) of US Provisional Patent Application No. 62/158,091 filed May 7, 2015. The contents of this provisional patent application are incorporated by reference in their entirety for all purposes.

The present disclosure relates to strontium-90 sealed sources such as may be used in ophthalmic treatment, other medical processes, brachytherapy processes, or industrial processes. In particular, it is required that the absorbed dose rate is relatively constant throughout the target volume of the target tissue to be treated with radiation (hereinafter referred to as "flat radiation profile").

The prior art of various types of radioactive or radioactive sources for medical, industrial, and other processes is well developed. For example, patented to Brigatti et al. on April 30, 2013, and literally assigned to Salutaris Medical Devices, Inc., “Method and apparatus for minimally invasive extraocular delivery of radiation to the posterior portion of the eye ( Patent Document 1 entitled "Methods and Devices for Minimally-Invasive Extraocular Delivery of Radiation to the Posterior Portion of the Eye)" discloses minimally invasive β rays from the radionuclide brachytherapy source to the posterior part of the eye. Dispensing applicators are disclosed. In particular, this applicator has been applied to treatment of various eye diseases such as wet type age-related macular degeneration, but is not limited thereto. As another conventional technique, "Brachytherapy Devices and Methods of Brachytherapy Devices and Methods of using the brachytherapy device and patented to White et al. on July 4, 2006 and transferred in writing to Theragenics Corporation. Patent Literature 2 entitled "Using Them)" and Patent Literature 3 entitled "Ophthalmic Brachytherapy Device" granted to Finger on September 3, 2002.

While these prior art techniques are well developed and suitable for their intended purpose, there is a need for further improvements in the radioactive sources used in the disclosed devices. In particular, if the radiation can be distributed in parallel rather than isotropically (“4π” in a spherical shape), it is possible to reduce radiation from the radiation source to the tissue to be treated while reducing the direct irradiation to the surrounding tissue not to be treated. It can be irradiated directly.

U.S. Pat. No. 8,430,804 US Patent No. 7,070,554 US Pat. No. 6,443,881

Therefore, the present disclosure aims to improve a radiation source used for brachytherapy, other medical applications, or industrial applications. In particular, the present disclosure aims to provide an improved radiation source for known applicators for the treatment of eye diseases. Eye diseases include, but are not limited to, wet age-related macular degeneration. This radiation source concentrates radiation on diseased tissue without the use of isotropic radiation, which is likely to unnecessarily expose surrounding healthy tissue to radiation.

This and other objects provide a β-radiation source, typically a β-radiation source comprising a strontium-90, with a radioactive insert exhibiting high activity in the periphery and low activity in the center. Will be achieved by providing. This means that the radioactive insert has an annular or ring-like shape (for example, a donut shape with a hole or opening in the center), or a disc with a small thickness or a central portion showing low activity. Can be achieved by having the shape of Furthermore, this is achieved by providing an outer packaging material that has a high shielding in the central part of the surface from which the therapeutic radiation is emitted, so that the radiation emitted from the central part of the radiation source is substantially attenuated. It A beta collimator grid is used as a further alternative.

Further objects and advantages of the present disclosure will be apparent from the following description and the accompanying drawings.

2 is a top view of a radiation source according to one embodiment of the present disclosure. FIG. FIG. 3 is a perspective cross-sectional view of a radiation source according to one embodiment of the present disclosure. 1C is a cross-sectional view taken along the line 1C-1C of FIG. 1A. It is a top view of the beta ray collimator grid of this indication. It is a figure which shows operation of a beta ray collimator grid in detail. FIG. 6 is a cross-sectional view of a radiation source according to a further embodiment of the present disclosure. FIG. 4 is a diagram relating to a radiation dose profile generated by the radiation source of FIG. 3. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 6 illustrates a radiation source according to further various embodiments of the present disclosure. FIG. 5 shows the placement of the radiation source relative to the human eye during treatment. FIG. 7 is a partial view showing FIG. 6 in more detail.

Reference will now be made in detail to the drawings, wherein like elements are designated with like numerals throughout the several views. 1A, 1B, and 1C show a radiation source (radioactive radiation source) 100 according to one embodiment of the present disclosure. The radiation source 100 typically comprises a radiation source envelope 102 made of titanium alloy, stainless steel, or similar material having suitable β-ray absorption and β-transmission properties. The radiation source outer packaging material 102 has a cylindrical outer wall portion 104, a circular open top portion 106, and a circular floor portion 108 forming a closed bottom portion. Typically, a circular lid 110, also made of titanium alloy, stainless steel, or similar material, is placed on the circular open top 106 and welded in place after all assembly is complete. By doing so, a low cylindrical structure is obtained. Typically, a cylindrical radiation source encapsulant-nesting member 114, also made of titanium alloy, stainless steel, or similar material, has a cylindrical inner wall 116 and a circular closed top 118. And a circular open bottom 120. A generally cylindrical volume or cavity 128 is formed within the inner cylindrical wall 116 (see FIG. 1B, showing a cavity without a strontium-90 insert), which volume or cavity 128 is typically A strontium-90 insert 130 of insoluble refractory material (β radiation source, see FIG. 1C) is retained. Insoluble refractory materials include ceramics, glass, or refractory metal composites such as strontium-90 compounds mixed with low density metals such as beryllium or aluminum. The β-ray collimator grid 140, which typically has a honeycomb structure, is disposed so as to contact the circular floor 108, that is, just above the closed bottom of the radiation source packaging material 102, and the strontium-90 insert 130 and the radiation. The source inner packaging material 114 is arranged so as to be in contact with immediately below the lower end of the cylindrical inner wall portion 116. The resulting radiation source 100 does not distribute the β-rays 1000 isotropically (in part due to the function of the collimator grid 140), but more β-rays 1000 are straight down, ie, FIG. 1C. Are distributed substantially parallel to each other as shown in FIG. 1 (see FIG. 1C). The resulting radiation source 100 is particularly well suited for use in the medical device of US Pat. No. 6,096,898, and the radiation distribution described above allows medical professionals to unnecessarily irradiate surrounding healthy tissue. Radiation to the treatment volume of the patient while minimizing the amount of For example, please refer to FIG. 6 and FIG. 7 showing the medical device 200 in which the radiation source 100 is arranged on the back side of the human eye 2000 and the human eye 2000 is irradiated with radiation horizontally.

It should be noted that the strontium-90 β-ray emissive insert 130 is formed from a variety of materials such as strontium ceramic, strontium glass, a tightly packed aggregate of ceramic beads (having various possible shapes), or a refractory metal composite. be able to. Refractory ceramics and refractory glasses containing strontium-90 can be formed from a wide variety of material combinations including, for example, metal oxides of aluminum, silicon, zirconium, titanium, magnesium, calcium, among others. _{SrF 2, Sr 2 P 2 O} 7, SrTiO 3, SrO, Sr 2 TiO 4, SrZrO 3, SrCO 3, Sr (NbO 3) 2, SrSiO 3, 3SrO · Al 2 O 3, SrSO 4, SrB 6, SrS _{, SrBr 2, SrC 2, SrCl} 2, SrI 2 , and, are believed to be able to add other materials chosen from strontium -90 compounds such SrWO _4, no other materials are not limited to. Also, beta emitters based on materials other than strontium-90 may be compatible with the present disclosure.

The beta collimator grid 140 is disclosed in more detail in FIGS. 2A and 2B. The beta collimator grid 140 is intended to block or absorb a significant portion of the non-orthogonal beta radiation, with little or no direct beta radiation or orthogonal beta radiation from the strontium-90. To do. The β-ray collimator grid 140 has a plurality of honeycomb-shaped open cells 142 (not to scale) partitioned by the wall 144 (see FIG. 2B for the wall 144). Direct β radiation or orthogonal β radiation passes through the openings or passages of the open cells 142 without hitting the wall 144, whereas non-orthogonal β radiation substantially hits the walls 144 of the honeycomb cells 142. Is absorbed by. In the typical example shown in FIGS. 2A and 2B, the total thickness is 250 microns, the bar thickness is 30 microns, the cell pitch is 260 microns, the opening diameter is 230 microns, and the direct radiation transmission is It is expected to be 78%. That is, 22% of direct beta radiation is attenuated. Those of ordinary skill in the art will appreciate, upon reviewing the present disclosure, that various dimensions and numbers may be used for similar applications. In some embodiments, a collimator grid 140 that has honeycomb cells 142 at the outer periphery and is substantially 100% transparent near the center is contemplated. It is believed that this results in an increase in direct radiation and that non-orthogonal radiation imparts its energy to the treatment area, which is also the target of direct radiation. Other advantages of using a collimator grid with a discoidal radiation source include a flat dose profile (ie, a profile where the absorbed dose rate is constant throughout the target volume of the treated tissue being treated with radiation). This profile shows that the dose rate is the same and the treatment dose is uniform in tissue with a certain volume at a certain depth without under or overexposure to different parts of the treatment volume of interest. Has the effect that Although a honeycomb hexagonal configuration is shown, the collimator grid 140 may have a square mesh shape or another mesh shape that is nested without gaps. The collimator grid 140 is capable of absorbing beta radiation and withstands normal operating conditions and accidental hazards such as 800° C. flame without adversely affecting the other components of the radiation source. It can be chosen from a variety of metals or non-metals to obtain. Typical preferred materials include iron alloys, nickel alloys, molybdenum alloys, copper alloys, gold alloys, carbon, and silicon. Those of ordinary skill in the art will appreciate, upon reviewing the present disclosure, that additional materials may be used in various applications. The collimator grid 140 may also be engraved on the circular floor 109 of the radiation source 100.

Since photons are less likely to scatter in the surrounding absorber than β particles, collimation is more effective with photons than with β particles. Photons are not easily attenuated (difficult to scatter), β particles are highly attenuated (easy to scatter, β particles have the same mass and charge as electrons, and β particles collide once To give more energy per hit). In addition, β particles are typically emitted with a spectrum from zero to a maximum value (2.28 meV in the case of Y-90 which is a decay product of strontium-90), and The attenuation and scattering properties differ significantly from the properties of monoenergetic photons that are attenuated only by electromagnetic field interactions.

In order to obtain a flat dose profile at an appropriate tissue depth in front of the β-source of the present disclosure, the difference between the central dose rate and the peripheral dose rate at the source surface is typically enhanced to increase the radiation dose. Need to output the source. In other words, if the dose profile is flat at the surface of the radiation source, it is considered that it is not flat at a distance from the surface of the radiation source due to β-ray scattering effect in the tissue. Therefore, it is typically desirable to obtain a lower annular dose profile at the source surface than at the periphery so that it flattens at the desired depth of the tissue by beta scattering in the tissue. .. As the distance and distance from the radiation source increase, the tissue dose profile is expected to become progressively more spherical due to stronger scattering and attenuation.

The absorbing tissue effectively acts as a source of scattered low energy radiation, which causes the dose profile to become non-collimated and more spherical at further distances from the radiation source.

FIG. 3 shows a sectional view of a radiation source 100 according to a further embodiment. The radiation source 100 is substantially rotationally symmetric, and its shape includes a cylindrical shape, a ring shape, and an annular shape. The capsule body 300, typically made of titanium or stainless steel, has a bottom floor 302 having a central flat 304. The central flat portion 304 (which enhances the β-ray shielding property in the central portion of the lower floor portion 302) forms an annular groove portion 306 between the central flat portion 304 and the cylindrical outer wall portion 308 of the capsule body 300. .. An upper end of the cylindrical outer wall portion 308 forms a circular opening for receiving the outer lid 310, and the outer lid 310 has a substantially circular cylindrical lower end portion 312, and has an expanded and contracted inner portion. It further includes a cylindrical blind central opening 314 for receiving the lid 316 and typically forming a secure friction fit with the telescoping inner lid 316. The outer lid 310, typically made of titanium or stainless steel and shown with an inner peripheral annular ridge 327, is typically welded to the capsule body 300 using conventional industry standards. The strontium-90 radioactive insert 318 (similar to insert 130 in the previous embodiment) has a circular or disc-shaped upper portion that engages between the lower end of the expandable inner lid 316 and the central flat portion 304 of the capsule body 300. Having 320. This structure is intended to prevent the strontium-90 radioactive insert 318 from wobbling. The strontium-90 radioactive insert 318 has a central protrusion 325 on its top surface. This central protrusion 325 strengthens the structure and prevents or minimizes sagging and possible peeling during manufacturing. The strontium-90 radioactive insert 318 further includes a peripheral annular portion 323 that extends into the annular groove 306 of the capsule body 300 and extends downwardly.

The strontium-90 radioactive insert 318 has an annular shape with a thicker periphery, which results in higher radiation emission in the periphery and lower radiation output in the center. This, combined with the high β-ray shielding property in the central region of the central flat portion 304, results in a flat beam profile and a more constant absorbed dose rate through the target volume of tissue to be treated in front of the radiation source. FIG. 5 shows typical values for the diameter and maximum height of the radiation source 100, which are 4.05 millimeters and 1.75 millimeters, respectively. In this example, the target treatment volume 400 has a diameter of 3.0 millimeters and, in the first case, a depth of 1.438 millimeters to 2.196 millimeters (average depth from the bottom surface of the radiation source 100 to the subject). In the second case, it has a depth of 1.353 millimeters to 2.111 millimeters (average depth from the underside of the radiation source 100 to the subject is 1.752 millimeters). The sclera 2002 (outer capsule) of the human eye 2000 typically has a radius of 11.50 millimeters (see also Figures 6 and 7). Those of ordinary skill in the art will appreciate, upon reviewing this disclosure, that varying structural parameters will result in different radiation distributions depending on the particular application.

5A-5F show a radiation source 100 according to six additional design embodiments of the present disclosure. The radiation source 100 of FIG. 5A is very similar to that shown in FIG. 3 and comprises a capsule body 300 having a lower floor 302. The inner wall of the lower floor portion 302 has a central flat portion 304 therein, whereby an annular groove portion 306 is formed between the central flat portion 304 and the cylindrical outer wall portion 308 of the capsule body 300. The upper end of the cylindrical outer wall portion 308 forms a circular opening for receiving the substantially cylindrical outer lid 310. The outer lid 310 is typically welded to the capsule body 300 using industry conventional standards. The strontium-90 radioactive insert 318 is formed in an annular shape having a central passage 319 by rotating a rectangular cross section about a central axis. The annular radiative insert 318 is disposed over the annular groove 306 and is supported by the central flat portion 304 and shoulders 308A, 308B formed inside the cylindrical outer wall 308. A cylindrical disk-shaped spacer 320, typically made of titanium or stainless steel, is disposed between the radiative insert 318 and the lower surface of the outer lid 310. Also, a cylindrical shielding insert 322, typically made of titanium or stainless steel, is inserted into the central opening 319. The shape of the strontium-90 radioactive insert 318 results in high radiation output in the periphery and low radiation output in the central opening 319. This, combined with the high shielding properties of the central region of the central flat portion 304 and the cylindrical shielding insert 322, results in a flat beam profile, which is absorbed through the target volume of the tissue to be treated in front of the radiation source. The rate is more constant (ie the resulting β-rays are anisotropic).

The radiation source 100 according to the embodiment of FIG. 5B is similar to the embodiment shown in FIG. 5A. The inner wall of the lower floor portion 302 does not have the central flat portion of FIG. 5A and is substantially flat. The annular strontium-90 radioactive insert 318 is secured to the cylindrical disc spacer 320 by a low melting glass adhesive 321 or similar construction. The cylindrical shielding insert 322 extends from the spacer 320 to the inner wall of the lower floor 302, resulting in a configuration with an annular void 306' under the annular strontium-90 radioactive insert 318. .. The shape of the strontium-90 radioactive insert 318 strengthens the radiation source at the periphery and eliminates it in the central opening 319. This, coupled with the high shielding of the cylindrical shielding insert 322, results in a flat beam profile and a more constant absorbed dose rate through the target volume of tissue to be treated in front of the radiation source.

The radiation source 100 according to the embodiment of FIG. 5C is similar to the embodiment of FIG. 5A. The annular strontium-90 radioactive insert 318 has a cylindrical disc-shaped central portion 318A, and further has an annular upper portion 318B and an annular lower portion 318C extending along the periphery thereof. The spacer 320 also includes a downwardly extending cylindrical skirt 320A that contacts the periphery of the annular strontium-90 radioactive insert 318 on the outside. The spacer 320 further includes a cylindrical central opening 320B that receives a variation of the shield insert 322. The shield insert 322 engages the cylindrical disc-shaped central portion 318A of the strontium-90 radiant insert 318 and is located below the annular upper portion 318B of the strontium-90 radiant insert 318. It further has a truncated cone portion 322A extending to the. With this configuration, the cylindrical disk-shaped central portion 318A is engaged between the truncated cone portion 322A extending below the shielding insert 322 and the central flat portion 304. Similar to the embodiment of FIG. 5B, an annular void 306' is formed between the annular lower portion 318C of the strontium-90 radioactive insert 318 and the inner wall of the floor 302. The shape of the strontium-90 radioactive insert 318 strengthens the radiation source at the periphery and reduces radiation from the cylindrical disc-shaped central portion 318A. This, combined with the high shielding in the central flat 304, results in a flat beam profile and a more constant absorbed dose rate through the target volume of the treated tissue in front of the radiation source.

The embodiment of FIG. 5D is similar to the embodiment of FIG. 5B, but with a shoulder 308A for supporting the annular strontium-90 radioactive insert 318 on the annular groove 306 inside the cylindrical outer wall 308. 308B. This eliminates the need to secure the annular strontium-90 radioactive insert 318 to the spacer 320 using a low melting glass adhesive 321 or similar construction. The shape of the strontium-90 radioactive insert 318 strengthens the radiation source at the periphery and eliminates it in the central opening 319. This, coupled with the high shielding of the cylindrical shielding insert 322, results in a flat beam profile and a more constant absorbed dose rate through the target volume of tissue to be treated in front of the radiation source.

The embodiment of Figure 5E is similar to the embodiment of Figure 5C. The annular strontium-90 radioactive insert 318 has a cylindrical disk-shaped central portion 318A and further has an annular lower portion 318C extending around its periphery. The absence of an annular top allows the spacer 320 to be simplified into a cylindrical disc shape. The shape of the strontium-90 radioactive insert 318 strengthens the radiation source at the periphery and reduces radiation from the cylindrical disc 318A. This, combined with the high shielding in the central flat 304, results in a flat beam profile and a more constant absorbed dose rate through the target volume of the treated tissue in front of the radiation source.

The embodiment of Figure 5F is similar to the embodiment of Figure 5E. The strontium-90 radioactive insert 318 is simplified to a disc shape rather than an annular shape. The spacer 320 also includes a downwardly extending cylindrical skirt 320A that contacts the periphery of the annular strontium-90 radioactive insert 318 on the outside. The strontium-90 radioactive insert 318 is fixed to the cylindrical disk-shaped spacer 320 by a low melting point glass adhesive 321 so as to be suspended on the central flat portion 304 and the annular groove portion 306. In this embodiment, it is also envisioned that at least a portion of the strontium-90 radioactive insert 318 is in contact with and supported by the central flat 304.

Further, as an alternative to the present disclosure, glass, such as glass that has been pre-melted in a stainless steel insert, glass powder that has been compressed with ceramic, glass powder that has been mixed with ceramic and then compressed, is effective. Fixing the insert may be mentioned. Also, as an alternative, a mechanical method, for example, a soft material such as copper, silver, or aluminum, or a spring of various types (corrugated, conical, stacking disc type, etc.) is used to provide an effective insert. It can be fixed. Further alternatives include utilizing the effective insert centering feature to prevent positional error, such as a tapered ceramic disc, or a disc with openings or protrusions that match the lid of the capsule body. To be

In this way, some of the above objects and advantages are most effectively achieved. While the preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that the invention is not limited in any sense thereby.

100 Radiation source 102 Radiation source outer packaging material 104 Cylindrical outer wall portion 106 Circular open top portion 108 Circular floor portion 109 Circular floor portion 110 Circular lid 114 Radiation source inner packaging material 116 Cylindrical inner wall portion 118 Circular closed top portion 120 Yen Shape Open bottom 128 Cavity 130 Radiation insert 140 Collimator grid 142 Open cell 144 Wall 200 Medical device 300 Capsule 302 Lower floor 304 Central flat 306 Annular groove 308 Cylindrical outer wall 310 Outer lid 312 Circular lower end 314 Cylindrical blind central opening 316 Flexible inner lid 318 Radioactive insert 319 Central passage 320 Cylindrical disk spacer 321 Low-melting glass adhesive 322 Shielding insert 323 Peripheral annular part 325 Central convex part 327 Inner peripheral annular ridge part 400 Target treatment volume

Claims (20)

A radioactive insert,
An outer packaging material around the radioactive insert,
A radiation source, which is provided adjacent to the radioactive insert, and which has a radiation collimator grid for directing the radiation emitted from the radiation source. The radiation source according to claim 1, wherein the radioactive insert emits β rays. The radiation source of claim 2, wherein the radioactive insert contains strontium-90. The strontium-90, strontium ceramics, strontium _{glass, SrF 2, Sr 2 P 2} O 7, SrTiO 3, SrO, Sr 2 TiO 4, SrZrO 3, SrCO 3, Sr (NbO 3) 2, SrSiO 3, 3SrO · The radiation according to claim 3, which is contained in a material or a compound selected from the group consisting of Al ₂ O ₃ , SrSO ₄ , SrB ₆ , SrS, SrBr ₂ , SrC ₂ , SrCl ₂ , SrI ₂ , and SrWO _4. source. The radiation source according to claim 1, wherein the radiation collimator grid has a plurality of open cells partitioned by a radiation absorbing material, and the open cells have openings through which radiation can pass. The radiation source according to claim 2, wherein the outer packaging material is formed of titanium or stainless steel. A radioactive insert having a central part and a peripheral part, wherein the radioactive dose is higher in the peripheral part than in the central part,
An outer wrapping material around the radioactive insert having a central portion and a peripheral portion, wherein one wall of the outer wrapping material has an outer wrapping material having a higher radiation shielding property in the central portion of the wall than in the peripheral portion of the wall. Radiation source. The radiation source according to claim 7, wherein the radioactive insert has an annular shape. The radiation source according to claim 8, wherein the annular shape is thicker in a peripheral portion of the radioactive insert than in a central portion of the radioactive insert. The radiation source according to claim 8, wherein a central portion of the radioactive insert has a convex portion. The radiation source according to claim 8, wherein a central portion of the radioactive insert has a passage. The radiation source of claim 11, further comprising a shielded insert that passes through the passage of the radioactive insert. 8. A radiation source according to claim 7, wherein the high radiation shielding in the central part of the wall is due to an internal flat part extending towards the radioactive insert. 14. The radiation source according to claim 13, wherein the central portion of the radioactive insert includes a passage, and the shielding insert penetrates the passage of the radioactive insert. The radiation source according to claim 13, wherein a central portion of the radioactive insert has a disc portion, and a thickness of a peripheral portion of the radioactive insert is larger than a thickness of the disc portion. The radiation source according to claim 15, wherein the inner flat portion extends toward the disc portion of the radioactive insert. The radiation source according to claim 16, wherein the outer packaging material further has an outer lid, and the outer lid has a blind opening for receiving the inner lid in contact with the radiation source. An annular radiant insert having a central passage,
A shielding insert that passes through the central passage,
A radiation source comprising an outer packaging material around the radioactive insert. The radioactive insert comprises strontium-90, and strontium-90 is strontium ceramic, strontium glass, SrF ₂ , Sr ₂ P ₂ O ₇ , SrTiO ₃ , SrO, Sr ₂ TiO ₄ , SrZrO ₃ , SrCO ₃ , Sr( _{NbO 3) 2, SrSiO 3,} 3SrO · Al 2 O 3, SrSO 4, SrB 6, SrS, SrBr 2, SrC 2, SrCl 2, SrI 2, and, on the material or compound selected from the group consisting of SrWO ₄ 19. A radiation source according to claim 18 included. A radioactive insert having the shape of a disc;
A radiation source comprising an outer packaging material around the radioactive insert, wherein one wall of the outer packaging material is a wall having an inner flat portion extending toward the radioactive insert,
Wherein comprises a radioactive insert is strontium -90, strontium-90, strontium ceramics, strontium _{glass, SrF 2, Sr 2 P 2} O 7, SrTiO 3, SrO, Sr 2 TiO 4, SrZrO 3, SrCO 3, Sr ( _{NbO 3) 2, SrSiO 3,} 3SrO · Al 2 O 3, SrSO 4, SrB 6, SrS, SrBr 2, SrC 2, SrCl 2, SrI 2, and, on the material or compound selected from the group consisting of SrWO ₄ Radiation source included.

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